MOT & ROADWORTHINESS · LAST REVIEWED: JUNE 2026
TL;DR: Headlamp aim is checked at every MOT, and an advisory means the alignment is slightly off but within tolerance. The car passed, but the note flags that the beam should be set correctly, because aim that is too high or too low can become a major defect.
Headlamp aim is one of the items every MOT assesses, because lights pointed too high can dazzle oncoming drivers and lights pointed too low reduce the driver's view. A headlamp aim advisory on the MOT means the tester found the alignment slightly out but still inside the permitted tolerance, so the vehicle passed.
The beam pattern is measured against the limits in the DVSA inspection manual using beam setting equipment. Aim can drift for several reasons, which is why an advisory is a common outcome and why it is worth understanding what the note is telling an owner.
KEY FACTS
- Headlamp aim is a tested MOT item, assessed against the DVSA MOT inspection manual using beam setting equipment.
- An advisory means the aim is slightly off but within tolerance; the vehicle passes.
- Aim that is outside the permitted limits, too high or too low, is recorded as a major defect and is a fail.
- The current defect grades of dangerous, major, minor and advisory were introduced in May 2018.
- Driving without a valid MOT can bring a fine of up to £1,000 under the Road Traffic Act 1988.
Why headlamp aim is tested
Correctly aimed headlamps light the road ahead without dazzling other road users. If the beam points too high it shines into the eyes of oncoming drivers, and if it points too low it shortens the distance the driver can see. The MOT checks the aim against defined limits to keep both effects within safe bounds.
The test uses beam setting equipment that shows where the cut-off line of the beam falls. The tester compares this against the tolerances in the inspection manual. An advisory means the beam is close to the edge of the acceptable range rather than outside it.
Why aim drifts and when it fails
Headlamp aim can shift for everyday reasons. A heavy load in the boot or a tow bar load raises the front of the car and lifts the beam, changes to suspension or tyres alter ride height, and a replaced headlamp unit may not have been set correctly. Some cars have a manual beam level adjuster on the dashboard that can be left in the wrong position.
Aim becomes a major defect, and a fail, when it falls outside the permitted limits in either direction. Many cars have an adjustment screw on the headlamp that allows the beam to be reset, so an aim failure is often a quick correction rather than a new part.
How aim is set and what to do
Headlamp aim is set with the car on level ground, at its normal ride height, using the adjusters built into the lamp. Because the correct setting depends on the vehicle, the alignment is normally checked with beam setting equipment rather than by eye. A garage can reset the aim during or after the test.
If a dashboard beam level control is fitted, it is worth setting it to the position that matches the load before the test, as a wrongly set control can cause an avoidable advisory or failure. Any adjustment to a faulty or insecure lamp should be carried out by a competent mechanic.
Bulbs, lamps and the wider lighting check
Headlamp aim is only one part of how lighting is assessed. The MOT also looks at whether the lamps work, whether they are secure and the right colour, and whether the lenses are in good condition. A cracked or heavily clouded lens that scatters the beam can be recorded as a defect even when the aim itself is acceptable.
The type of headlamp can affect what the tester looks for. High intensity discharge and LED units, and headlamps fitted with self levelling or cleaning systems where required, have additional checks because they can dazzle more if they are not working correctly. A self levelling system that has failed can lead to a defect being recorded.
A replacement bulb that is the wrong type or colour can also cause problems. A bulb that is too bright, the wrong colour temperature, or not matched to the lamp can produce a beam pattern or colour that does not meet the requirements, turning a simple swap into a failure. Matching the bulb to the vehicle specification avoids this.
Because the front lamps work as a pair, it is worth checking both sides together. A difference in brightness or colour between the two headlamps, or one lamp that is misaimed while the other is correct, is easier to spot when they are compared, and fixing both keeps the lighting balanced and within the rules.
Rear and auxiliary lighting forms part of the same overall check. Brake lights, indicators, the rear fog light, the registration plate lamp and any reversing lights are all assessed for operation, colour and security, and a fog or reversing lamp that stays on when it should not can be recorded as a defect. Because so much of lighting is straightforward to check by eye, walking around the car with the lights on, ideally with a second person to watch the brake lights, removes many of the simple faults before the headlamp aim is even measured. Carrying a spare set of common bulbs and knowing how they are changed on the vehicle can turn a potential failure into a quick fix, since a single blown bulb found on the day is among the easiest faults to put right.
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DISCLAIMER: This guide is general information, not professional advice. MOT rules and fees are set by the DVSA and can change. Check gov.uk for current requirements before acting.
Frequently Asked Questions
What does a headlamp aim advisory mean?
It means the tester found the headlamp alignment slightly off but still within the permitted tolerance, so the car passed. The note flags that the beam should be set correctly before it drifts outside the limits.
Will headlamp aim fail an MOT?
It can. Aim that is outside the permitted limits, pointing too high or too low, is recorded as a major defect and is a fail. Aim that is only slightly out is usually an advisory.
Why has my headlamp aim changed?
Aim can drift from a heavy load in the boot, a change in ride height, a replaced headlamp unit, or a dashboard beam level control left in the wrong position. Many of these can be corrected with the headlamp adjusters.
Can headlamp aim be adjusted easily?
Most cars have adjusters built into the headlamp that allow the beam to be reset, so an aim issue is often a quick correction rather than a new part. It is set using beam equipment on level ground at normal ride height.
